Last month, prosecutors filed felony charges against one officer accused of beating a female bartender, and six other officers were removed from street duty after they were accused of assaulting four businessmen in a bar.

Superintendent Philip J. Cline, who took over as superintendent in November 2003 and had been expected to retire later this year, said at a news conference he would stay on until a replacement was found. He said he told Mayor Richard M. Daley of his intention Monday morning.

"Mayor Daley has given me a once-in-a-lifetime opportunity to lead the best police department in the country, and I thank him for that," said Cline, 57.

To the city's police officers, he said: "I encourage all of them to rise above any controversy and stay focused on the mission."

After the two videotapes surfaced, Cline said he would change the way the department responds to allegations of misconduct, including moving faster to get officers accused of misconduct off the street. His early retirement announcement came as a surprise.

The department was internationally vilified after the bar surveillance footage of an off-duty officer pummeling a female bartender half his size was broadcast worldwide through 24-hour news channels and on YouTube.

Police said the footage showed Anthony Abbate, a 12-year veteran of the force, punching, kicking and throwing 24-year-old bartender Karolina Obrycka to the floor after she reportedly refused to continue serving him drinks. The Polish immigrant suffered bruises to her head, neck, back and lower body, according to her attorney, Terry Ekl.

Officials have been criticized for waiting a month to arrest Abbate and for initially charging him with a misdemeanor.

In his brief statement on Monday, Cline also alluded to the apparent effort by police officers to help Abbate enter and leave a court building without having to face the media outside.

That caused an outcry in the media about the way police officers protect fellow officers accused of breaking the law.

The department has not released footage from the other confrontation, involving the four businessmen on Dec. 15. Police had been called that night, but a sergeant who was among the officers involved in the fight waved them off, Cline said. He announced last week that the six officers had been taken off street duty.

During Monday's news conference, Cline did not say what role the incidents played in his announcement, only referring to them obliquely as "these times of challenge."

But in recent days, he has clearly been embarrassed. He said Abbate "tarnished our image worse than anybody else in the history of the department," and after the second incident said he was "disgusted to witness this type of conduct" by officers.

The Basmanny Court of Moscow arrested Michael Calvey, the founder of Baring Vostok investment fund, on allegations of embezzling 2.5 billion rubles from Vostochny Bank. Calvey will be held in custody until April 13